[daveone23]

Need a schematic or manual for the 664. The 663 may be similar.

[DaleHCook]

Radio City Products Co. information is almost impossible to find, aside from advertisements in trade journals such as "Service." 664/663 service information is not found on any of several sites where I look for schematics and manuals. I did see a couple of booksellers listing copies of the 664/663 manual for sale at:

https://www.bookfinder.com/search/?ac=sl...520manuals